A telephone system often has a number of telephones at a subscriber side. These telephones are coupled to a central office switch (CO) or private branch exchange (PBX). One or more trunk lines can couple the CO or PBX to a larger telephone network. A CO or PBX can serve one or more exchanges. An exchange is identified by a dialing prefix (3 digits are used in North America). Each telephone is assigned an extension (4 digits are used for an extension in North America). Typically these extensions are fixed during installation. See, Gilbert Held, Voice Over Data Networks, “Telephone Operations,” Chapter 5, pp. 113–26 (McGraw-Hill Companies, Inc.: U.S.A. 1998).
A number of services or features are available in today's telephone systems. These features include call forwarding, ringing, button-map assignments, voice mail and message retrieval delivery, and others. Information identifying the particular features available at a telephone is stored in a memory at the CO or PBX. For example, a table entry associated with a particular extension can include information identifying the features available at the telephone. User settings and choices such as ring style, customized button-map assignments, greeting information and call forwarding instructions are also associated with a particular telephone. Information identifying user settings and features may be stored in memory at the telephone set or at the CO or PBX.
Once set up, all of this configuration information for a telephone is associated with a particular extension and fixed. While this may be acceptable for a telephone user who uses the same telephone at the same location, it is limiting in a variety of applications and settings. The limitations are especially burdensome when users need to be able to access multiple telephones at multiple locations. The effort a user expends optimizing settings and features for a particular telephone is lost when the user needs to use a different telephone at another location. This can impair productivity as a user may not be able to leverage available telephone features effectively.
For example, in some workplaces, a user may often work at multiple locations splitting time between a private office and a laboratory. Both of these locations may have telephones; however in many cases, the user may not be able to configure the laboratory telephone because it is shared by multiple users. This can cause frustration and limit productivity as a user may not be able to leverage certain telephone features while in the laboratory at a different extension and telephone.
Similarly, in many environments, telephones may be used by a number of different people. For example, a realty company may have several different extensions available at an office. Because the number of realtors can exceed the number of telephones, it is often impractical to assign each realtor a dedicated extension and telephone. Instead, the realtors are expected to share telephones on an as needed basis as they are available. Realtors may access the telephones at different times depending upon their schedules, the availability of the telephone or the office associated with the telephone, etc. This means a realtor is unable to customize settings for a particular telephone because he or she must move across different telephones. Configuring a particular extension is then limited to a relatively generic set up that will be acceptable to many different users.